Tuesday, June 5th, 2012 at 5:03pm

The proportion of Americans in their prime working years who have jobs is smaller than it has been at any time in the 23 years before the recession, according to federal statistics, reflecting the profound and lasting effects that the downturn has had on the nation’s economic prospects.

By this measure, the jobs situation has improved little in recent years. The percentage of workers between the ages of 25 and 54 who have jobs now stands at 75.7 percent, just a percentage point over what it was at the downturn’s worst, according to federal statistics.

Before the recession the proportion hovered at 80 percent.

While the unemployment rate may be the most closely watched gauge of the economy in the presidential campaign, this measure of prime-age workers captures more of the ongoing turbulence in the job market. It reflects “missing workers” who have stopped looking for work and aren’t included in the unemployment rate.

During their prime years, Americans are supposed to be building careers and wealth to prepare for their retirement. Instead, as the indicator reveals, huge numbers are on the sidelines.

“What it shows is that we are still near the bottom of a very big hole that opened in the recession,” said Heidi Shierholz, an economist at the Economic Policy Institute, a left-leaning think tank.

The falloff has been sharpest for men, for whom the proportion had been on a slow decline before the recession. The percentage of prime-age men who are working is smaller now than it has been in any time before the recession, going all the way back to 1948, according to federal statistics. The proportion of prime-age women is at a low not seen since 1988.

The nation’s unemployment rate has shown signs of improvement, ticking down from 10 percent to 8.2 percent, but recent job-creation numbers have been dismal. If it tallied people who have given up looking for jobs, it would certainly be higher.

The ratio of employment to population, which economists refer to as “epop,” “is a much better measure for what people are experiencing in the job market,” Shierholz said. “The unemployment rate is screwy right now because the labor market is so weak that people have stopped trying.”

Shierholz estimates that about 4 million workers have simply stopped looking, and so do not show up in the tally used for the unemployment rate.

According to the most recent Washington Post-ABC News poll, the issue of paramount interest to voters is the economy and jobs, with more than half describing it as the “single most important issue.”